21110520 has 128 divisors (see below), whose sum is σ = 68428800. Its totient is φ = 5193216.

The previous prime is 21110513. The next prime is 21110543. The reversal of 21110520 is 2501112.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21110496 and 21110505.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 107062 + ... + 107258.

It is an arithmetic number, because the mean of its divisors is an integer number (534600).

Almost surely, 2^21110520 is an apocalyptic number.

21110520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21110520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34214400).

21110520 is an abundant number, since it is smaller than the sum of its proper divisors (47318280).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21110520 is a wasteful number, since it uses less digits than its factorization.

21110520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277 (or 273 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 21110520 is about 4594.6185913523. The cubic root of 21110520 is about 276.3755651749.

Adding to 21110520 its reverse (2501112), we get a palindrome (23611632).

It can be divided in two parts, 211 and 10520, that added together give a triangular number (10731 = T₁₄₆).

The spelling of 21110520 in words is "twenty-one million, one hundred ten thousand, five hundred twenty".